Question 1
Consider the timed token algorithm of FDDI. Assume that the token size is negligible, and also that
propagation delay and store-and-forward delay at each node is negligible.
Assume that TTRT = 100 msec, we have five stations, and that each stat

Packet Switching
1
What is a network?
! Network: a collection of computers,
each with its own unique ID (address),
so that each computer can send a
message to any other computer in the
network.
! Is Ethernet a network?
! Is 802.11 a network?
2
Outline
! W

CS 4390/5390 HW1 Spring 2014
All questions count equally. The TA will give credit for effort.
Question 1 (OSI Layers)
=
a) list the seven layers of the OSI model and give a one or two sentence description of the functionality of each.
Layer 7, Applicati

1
Sequence Numbers
To distinguish between frames, we add a sequence number to each frame.
Frame messages are of the form frame(i) where i is a sequence number.
o frame(0) is the first data message, frame(1) is the next data message,
frame(2), frame(3),

Broadcast
p has a single data item called p.d (non-changing)
All other q, qp, want to learn the value of p.d
Topology is unknown
Solution:
Every process has a Boolean variable, rcvd, initially false.
At p: p sends bcp(p.d) to all its neighbors
p sets p

Routing
Distance Vector
1
Routing
l
l
l
Definition
The task of constructing and maintaining the
forwarding table in datagram routing
Goals
Obtain the best path from each node to each
other node.
Conceptually
We will describe the algorithm for a general

Error Detection/Correction
Messages are a sequence of bits, 0s and 1s
Bit corruption channel changes the value of some bits
0 1
1 0
Corruption may be random for each bit (thermal noise for example ).
Corruption also may occur in bursts
Corruption bur

Cyclic Redundancy Check (CRC)
To each message, we will append n additional bits, where n is a constant.
Let m be the message size.
Note that m is not constant, the technique works for messages of any size.
We assume we have a constant G, which is a string

Internetworking
Computer Networks
Dr. Jorge A. Cobb
Internetworking
l
What is an internetwork?
Many networks interconnected, but provide the illusion of having a single
network
Each network has its own addressing and routing mechanism.
To cross from on

Introduc)on
Introduc)on to the course
Computer Networks
The University of Texas at Dallas
1
www.utdallas.edu
Expecta)ons
This course is about:
General purpose computer communica)on
networks
Fundamental concepts and princi

Greetings to all,
I wanted to give you, in a nutshell, the proof as to why distance vector routing, regardless
of the initial state of its routing tables and its cost tables, will converge to a state in which
all nodes have the least-cost path to the dest